Development and validation of concurrent preimplantation genetic diagnosis for single gene disorders and comprehensive chromosomal aneuploidy screening without whole genome amplification

Capsule:
This study establishes a method for simultaneous comprehensive chromosomal aneuploidy screening and preimplantation genetic diagnosis for single gene disorders from the same trophectoderm biopsy using quantitative real-time polymerase chain reaction.

Authors:
Rebekah S. Zimmerman, Ph.D., F.A.C.M.G., Chaim Jalas, Xin Tao, M.S., Anastasia M. Fedick, Ph.D., Julia G. Kim, M.D., Russell J. Pepe, B.S., Lesley E. Northrop, Ph.D., Richard T. Scott Jr., M.D., H.C.L.D., Nathan R. Treff, Ph.D.

Volume 105, Issue 2, Pages 286-294

Abstract:

Objective:
To develop a novel and robust protocol for multifactorial preimplantation genetic testing of trophectoderm biopsies using quantitative polymerase chain reaction (qPCR).

Design:
Prospective and blinded.

Setting:
Academic center for reproductive medicine.

Patient(s):
Couples indicated for preimplantation genetic diagnosis (PGD).

Intervention(s):
None.

Main Outcome Measure(s):
Allele dropout (ADO) and failed amplification rate, genotyping consistency, chromosome screening success rate, and clinical outcomes of qPCR-based screening.

Result(s):
The ADO frequency on a single cell from a fibroblast cell line was 1.64% (18/1,096). When two or more cells were tested, the ADO frequency dropped to 0.02% (1/4,426). The rate of amplification failure was 1.38% (55/4,000) overall, with 2.5% (20/800) for single cells and 1.09% (35/3,200) for samples that had two or more cells. Among 152 embryos tested in 17 cases by qPCR-based PGD and CCS, 100% were successfully given a diagnosis, with 0% ADO or amplification failure. Genotyping consistency with reference laboratory results was >99%. Another 304 embryos from 43 cases were included in the clinical application of qPCR-based PGD and CCS, for which 99.7% (303/304) of the embryos were given a definitive diagnosis, with only 0.3% (1/304) having an inconclusive result owing to recombination. In patients receiving a transfer with follow-up, the pregnancy rate was 82% (27/33).

Conclusion(s):
This study demonstrates that the use of qPCR for PGD testing delivers consistent and more reliable results than existing methods and that single-gene disorder PGD can be run concurrently with CCS without the need for additional embryo biopsy or whole genome amplification.

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